Automatic syringe



Aug. 5, 1952 KOLLSMAN 2,605,765

AUTOMATIC SYRINGE 2 SHEETS-SHEET 1 I Filed June 5, 1947 INVENTOR.

@ L KQLLSMHN A; ATTORNEY Aug. 5, 1952 P. KOLLSMAN 2,605,765

AUTOMATIC SYRINGE Filed June 5, 1947 2 SHEETS-SHEET 2 /0/ Fig. 6

Fig. /0

INVENTOR,

ATTORNEY Patented Aug. 5, 1952 "T' UNITEDqSTATES PATENT OFFICE PaulKollsman, New York, N. Y. Application June 5, 1947, Serial No. 752,787

This invention provides a device for continuously and automaticallyadministering medicinal compositionsin fluid fornito a patients body.

' In the treatment of disease by hypodermic or oral medication, it isfrequently the aim to maintaina certain concentration of amedicinal'composition in the body fluids of the patient over extendedperiods of time. The concentration must be sufiiciently high to producethe desired beneficial effects, but should, at the same time, be as lowas possible so that the total quantity of the medicinal compositionwhich is administered and its toxic effects are small.

The body eliminates or inactivates at a certain rate medicinalcompositions introduced into it. It is therefore evident that a dose ofa medicinal composition administered sufficiently small to make itstoxic efiects tolerable soon loses its effectiveness.

In cases where, for the purposeof treatment, a certain concentration ofmedicinal compositions in the body fluids hasto be maintained over ex-vtended periods of time, it has become the generally accepted practice toadminister doses of medicine repeatedly within predetermined intervalsof time in order to counteract the tendency ofv the body to eliminate orinactivate the compositions. As a result, the total of the individualdoses of compositions isconsiderably in excess of the quantity needed ifit were possible to main: tain the concentration within the body fluidsconstant. A certain amount of the compositions is thus wasted. It isalso evident that the toxic effect of individual periodicadministrations of doses isrelatively great since the concentrationimmediately following an administration must necessarily be greaterthanthe required minimum in order that the effect of the dose be extended.

The present practice of administering medicinal compositions therefore Iputs an unnecessary burden on the patients system.

If the time intervals between administration of individual doses isshort, for example, of the order of two hours, and if the total time oftreatment is relatively long, for example two to four days, the patientis robbed of the benefit of natural and uninterrupted sleep. Dosesadministered in the form of hypodermic injections may therefore add upto a total of48 individual injections for a certain treatment. Suchtreatment is necessarily very painful to the patient. It is also Thepresent invention overcomes the'various '7 Claims. (Cl. 1Z8-218)disadvantages of the conventional practice of administration ofmedicinal compositions in providing an apparatus for the continuousadministration of medicinal compositions at a predetermined rate overextended periods of time.

The novel device consists, in effect, of an automatic syringe includingan injection needle, a charge of medicinal composition in fluid form, aself-contained source of power, and means for controlling the rate atwhich the composition is continuously discharged through the injectionneedle. The device is sufficiently small so that it may be: attached toa portion of the patients body. Once attached, itmay be'carried withoutinterference or substantial annoyance of the patient over periods oftheorder of several days during which period a continuous rate ofdischarge of fluid composition is maintained.

The concentration of the-composition and the rate of its discharge areso selected that a predetermined minimum concentration'of thecomposition is maintained in the patients body throughout the treatment.Thejvolume is so selected as to be readily absorbable' withoutformingp'oo1s-ordepots;'

Since thevolumetric 'quantity per hour is extremely small, it isnot'necessary to insert the injection needle deep into a muscle, but itis sufficient in most instances to insert it slightly below' the skin.This particular property and feature of the presentinvention greatlyreduces the discomfort of thep'atieht. The injection needle canaccordingly be {made thin and relatively short. 1

injection devices embodying the present invention may be made for singleuse, to be discarded after thetreatment, or may be made asrechargable'unitssuited forirefilling. They may also be constructed oftwo'units, a re-usable power unit to which adisposableinjection unit isattached.

The various objects, features and advantages of this invention willappear more'fully from the detailed description which followsaccompanied by drawings showing, for the purpose of illustration,preferred embodiments of the invention. The invention also consists incertain new and original features of construction and combination ofelements hereinafter set forthand claimed.

Although the characteristic featuresof this invention which are believedto be novel will be particularly pointed out in the claims appendedhereto, the invention itself, its features and advantages, andthemanner'in which it may be carried out-may be better understood ,byreferring to the following descriptiontaken in connec timing unit towhich a disposable injection unit isattached;

Figure 6 is a detailed view, partly in section, of

an injection unit including a separate injection needle;

Figure 7 is a sectional view of an automatic syringe powered 'by'aspring motor; Figure '8 is a detailed view of elements er the device ofFigure "7, a section beingtaken "on line 8'8 of Figure 7;

Figure'9 is 'a plan view 'of the device shown in Figure 8; 'and 'Figu're1.0 is 'a sectional view of anautomatic syringe including a power unit'o'perat'i'ng with gas pressure. V

In the following description and'i'n the claims, various details will beidentified by specific names for convenience. The names, however, areintended to be as generic-in their application as the art will permit.Like reference characters refer'to like parts in'the several figures ofthe drawings.

In the drawings accompanying, and forming part of, this specification,certain'specific disclosure of the invention, is made'for'thepurpose ofexplanation of broader aspects ofthe invention, but it is understoodthat the details may be modified in various respectswithout'departurefrom the principles o'fthe invention and that the invention may beappliedto other 'structuresthan the ones shown. Any permissible'changesinthe constructions disclosed herein'must fall within the purview of theclaims appendedhereto.

The syringe shown in Figurefl comprises 'a housing ll consisting oftwotubular portions'lZ and'l3. A variable'volume chamber I4 is formed inthepreferably transparent housing portion 12 by a movable wall which,"in the illustrated example has the form of a free movable piston l5sealed with respect to the inner cylindricalsurface I6 of the housing by-a gasket ll. The variable volume chamber M has a discharge passage l8leading to a hollowinjectionneedle i9 which extends approximately atright 'anglesiwith 'respect to the bottom'surf'ace '20 of the housing 'II. During non-use of the syringe, the injection needle is protected by aremovable cap 2l preferably seated on a knob-shaped projection 2 l Theprojection 2| besides forming a tight seatfor the cap 2! facilitatesinsertion of therelatively short needle l9 through the skin which, wereit not for the projection, wouldyield appreciably without beingpenetrated by the needle, or if punctured, would not permit the needleto penetrate to its full length.

The cap 2| is preferably made of relatively rigid material such as metalora plastic and is lined on the inside with a relatively soft'liner 2 ladapted to form a seal for the needle IS.' The liner 2 I' may be made ofa soft or pliable material, for example soft rubber, into which the ,13.cured at 21v and forms the seat for a helical 4 needle'is pressed whenthe cap 21 is attached. The liner 2| seals the point of the needle toprevent accidental discharge of medicinal fluid, if the fluid is underpressure, and provides mechanical protection for the needle. Inaddition, the cap maintains the needle sterile until its actual use.

The two portions of the housing l2 and I3 are secured together by athreaded plug 22 which also forms a partition in the housing,'thethreads being cemented for tightness.

A power piston 23 sealed by a gasket 24 is movable in the rearwardhousing portion [3 and has a piston guide rod 25 whose end passesthrough a collar '26 closing the end of the housing portion The collar26 is threaded or otherwise sespring 28 Whose other end bears againstthe power piston 23.

The power piston may be maintained in inactive position in which thespring 28 is compressed by "ar'elease cap'29 sho'wn'in Figure 2. The cap29 h'a's'an internal threadeil fitting on a corresponding'thread 3 lonthe end portion: of the piston 'gui'derod 25. r

The plug '22 forms a' "dividing "wall between chambers 32 and 33. In thecondition in which the device is ready for use, the chamber 33 is filledwitha highly viscousv liquid, preferably'one having a low temperaturecoefilci'entof viscosity, for examplea silicone li'quidof 'appropriateviscosity which may range up to 750,000centistok'es or over, theviscosity being determined by the length of the periodduringwhichithesyringe is tooperatecontinuously'. The liquid in the-chamber 33 maybeforced into'thechamber'flz'through a restricted passage fof preferablylaminar flow characteristics, for example a capillary passage. Thispassage may conveniently be formed'by'the fine threads of a screw 34threaded into 'a cylindricalhole 35' in theplug '2 2,ithe diameter ofthe hole 35 being slightly less than the outside diameter'of the screwbut slightly more than'its core diameter so that a helical passage 35 isformed along therootof the threa'd'whose length may be adjustedby'varying thedepth to which the'screwextends'into the hole 35. Acylindrical hole, as-shown in the drawing, has been found satisfactoryfor *the purpose although it is, of course, possibletoprovideinternalthreadsin the hole, the profiles'of'the threadsbeing'so selected as to provide for-clearance resulting in a capillary passagealong the core or crest 'of-the screwed:

The variable volume chamber I4 is filled with am'edicinal compositionoffiuid formtobe injected; and thechamber 3?;60111331115 normally, beforethe-device is put 'in ope'ratibn, just sunlcient viscous liquid toresult'in immediate-movement of the piston i5 if further liquidis'displaced from chamber '33; into chamber 3 2.

The device is filled'with amnedicinal fluidat the chemical factoryorlaboratory distributing the device. The liquid in chamber "3 3 is-soselected and the flow resistance of the-capillary passage 36 between thechambers 32 and 33*isso selected that after release of the powerpiston-2 3 the piston will come to the end of its stroke after apredetermined period of time which may be; of the order of 1 48: to ,72hours or more.

The device is applied to a'p'ortion ofthe'b'ody after removal'of theprotecting cap 2! fromthe injection needle; Thehousinghas anappropri-'ately [shaped bottom surface 2 0 which may, for example, be fiat andbe'provi'ded with'ja' tacky composition 6 similarv to that used"onadhesive' tape in order to prevent'shifting o'f'the' housing after itis applied. to. the body. The housing may be=provided with anenlargedhead 31 to prevent tilting, and may. be. held .in place by a bandage oradhesive .tape.

Shortlybefor'ethe device is applied, the release cap 29 is removed from,the end of the piston guide rod 25, whereupon the spring 28 expandstending to move the power piston 23 towards the partition plug 22against the resistance of the viscous liquid in chamber '33 which nowflows slowly through the capillarypassage 36 into chamber 32 and, inturn, moves. the piston I5 which then displaces fluid from the chamberl4 through the injection 1168611619-5 I I ,Air is admitted into thespace 38 in back of the power piston 23 through ,a vent passage 39inorder, to prevent suction from being built up therein due to themovement of the power piston 23. For practical purposes, a loose fit ofthe piston guide rod 25 in the collar 25 is sufficient to provide thisvent. 1 p

The spring 28 is preferably so dimensioned that only a fraction of itspower is spent during the travelof the power piston 23 from one extremeposition to the other in order to eliminate the effect of decreasedspring power due to Hookes law. However, in some instances, a slightdecrease in the rate of injection towards the end of the treatment isdesirable. It is evident that this can be accomplished very convenientlyby providing for a corresponding drop in spring power. A V V s ,1

The timing of the device is very accurate since changes in the viscosityof the liquid dueto changes-in temperature do not occur by reason of thefact that the injection device is wornron the body of the patient,whereby the device is maintained at a substantially constant temperaturethroughout the treatment.

Theprogress of the injection, may be observed and the total volume ofinjected liquid be read at a graduation printed or engraved onthetransparent housing l2 cooperating with the edge of the piston 5. v j jThe syringe shown in Figure 4 comprises a housing 40 in which a steppiston 4| is movable. The step piston 4| has gaskets 42 and 43 andsubdivides the interior space of the housing into chambers 44, 45, and4.6.. The chamber 46 is closed by a threaded plug 41 having a ventpassage 48 therethrough and having a further centrally located hole 49through which a release stem 50 extends. v 1

The chamber 44 is filled with a charge of a highly viscous liquid whichunder pressure may flow into the chamber 45 through a cylindricalpassage in the piston including, acapillary restriction .52 formed by ascrew 53 threaded into the cylindrical passage 5|, the inner diameter ofthe cylindrical passage 5| being slightly less than the outside diameterof the screw and slightly more than the core diameter of the screw.

The chamber 45 is filled with a charge-of medicinal fluid to be injectedwhich is discharged through an injection needle 54 communicating withthe chamber 45through a passage 55. The injection needle 54 extendssubstantially normal with respect to the bottom surface 56 of thehousing 40 which may have a layer of tacky material 51 applied to it. I

A helical spring 58 bears against the piston 4| with one end and againstthe threaded plug 4'! with the other.- The power. ofv thespring 58 maybe released-by unscrewing the release stem 50 from the piston 4| andthusremovingi it from the device. .Removal ofthe stem 50 opensthepassage 5|. through the piston and permits viscous liquid toflowfrom'chamber144 into chamber 46 while at the same timethe piston 4|moves in a direction to force medicinal fluid. from thechamber.45outthroughthe needle 54.. y 7

- The :device may be initially filled by feeding viscous liquid intovthe chamber 44 through a filler plug 59 and by filling. the chamber 45with medicinal fluid. through a similar plugsfifl leading toapassage61.1 m g The. syringe of'Figure applied and used in the-same manner asthe form of syringe shown in Figure 1. It is fixed in place by the tackycomposition 51- on its under surface 56 and is secured by bandages ortape. The forxn of syringe shown inIFigureA is particularly suited forone-time use, tQbediscarded after use. The step arrangement of thepiston provides for a relatively large-chamber for medicinal fluid and arelatively small onefor the viscous liquid so that only a small quantityof viscous liquid is required. v The automatic syringe shown in Figure 5comprises a re-useable power unit .62 to which a disposable injectionunit. 63.,may-be attached. The injection unit is preferably transparentandmay be provided. with a .graduated scale It]. i The power unit 62consists of a housing 64 divided into chambers 65, and 6G by a wall or apartition, 51 having a gasket 68 therein. A power piston 59 isimovablein the chamber 55 in the housing and isiacted upon by ahelical spring 10bearing 'againstthe piston with one end and against the wall 61 with theother. A passage 1| provides communication of thechamber 65 with theatmosphere. e I

The power piston 69 has a piston rod I2v attached to it which passesthrough the partition wall 51 andis attached to, or integral with, adamping piston 13 provided with v gaskets 14. The damping piston dividesthe chamber 66 into further chambers 15 and 16. The end of thechamber'lfi is closed by a plug H through which the piston rod 12.extends. The piston .73 is sealed-against the plug 11 by a gasket I8.

The damping piston 13 has a restricted capillary passage 1 9 through itformed by a screw threaded intothe passage so that a helical capillarypassage is formed along the screw surface.

A second passage 8| is normally closed by a check. valve shown, as aball 82 forced against its valve seat by a spring 84. The spring bearsagainst the ball with one end and against the threaded plug 85 with theother. The threaded plug 85 has a passage 86 therethrough.

The end of the housing .64 is threaded at 81 and may be connected to theinjection unit or cartridge 63 containing a charge ofmedicinal fiuid,ina chamber 88. A discharge passage 89 .leadsfrom the chamber 88 to aninjection needle 90. The chamber 88 is sealed by a movable piston 9|having a gasket 9|. The piston 9| is in contact with the power piston 69and may be mechanically moved by it in order to force fluid out of thechamber 88'through the needle 90'.

The device is put in operation by moving the piston rod in a directionto compress the spring 10. During this movement damping liquid flowsfrom the chamber 16 into the chamber 15 through the passage 8| and pastthe check valve 82. An injection unit is then attached-to the powerunitBZ whereafterthe device is ready for immediate use. The power piston69 slowly urges the piston 9| in the injection unit in the directiontodischarge fluid therefromnthe; rate;;f: dise charge beingudetermined:by the viscosity of. the damping liquid-in chamberi'li, theilow.resistance of the capillaryipassagelszand the iorce;ofrthe spring 10.

The housing :oiithe power-unit rorrof .thejniection unit, or both,;maybe:proyided;on'its 111116.61 surface with a coating :oftackylmateria-ljto maintain the syringe fixed: againstithe surface -ofthe body of the patient to which. itiis attached; Progress of thedischarge of medicinal liquid may be observed by reading agraduation-.92:- on. the piston rod 12- against the'z end 'suriacezrofz.the plug. I

The injeetionunit 63". shown in Figure.. 6:has a flexible tube -=93-co'rmected.n.tosfits discharge passage 8 9 leading tofza needle ahead.Qhcarrying an injection needle; The -hcadp94" iisa .;sma1l housinghaving on its other side.;a layer sot-an adhesive substance '96. i Theinjection1unit,.:B3f may be-used in place .of the aunitl63 shown. inFigure and permits insertion .of the "needle .35 at a point remote fromthe power and injection unit to which it is attached. The.hea L94;:afterv insertion of the needle 95', is tapedorotherwise secured to thepatients skin, the adhesiveyflfi serving toprevient small movementsoithe head thereby preventing irritation at-thepoint of injection.

Figures 7 to 9' illustrate an injection. device comprising basicallyanescapement controlled spring-motor or watch movement. -A power unit 91is housed in a casting 98. resembling. the case oi-a wrist watchhaving-lugs 99 -towhich securing straps may be attached. The movementotlthe watch is conventional and comprises the usual main spring, gears,and escapement. Because of thi conventional construction, these elementsare not shown in detail. The watch may beprovided with theconventional'dial N10. The .power shaft llll of the main spring barrelis extended and carries apinion I02 meshing witharackqlflil', the teethof the rack being ior-mediin when HM which is longitudinally movableand-also r0.- tatable in spaced bearings 405' and 106; 1 VA power pistonIt? is connected to oneend of theshaft 184 and-a'crown 1 031's connectedto-the other end permitting turning of thelshaft" lfitun'til its .flatto portionlfi9-faces-the pinion Ininverted position the shaft 1% may belongitudinally moved with respect to thepinion lfiland'be reengaged inadifierent longitudinal positionby turning; the shaft lfltsoz'that-itsteeth re-engage the pinion 182.

The power piston F61 bears against a piston 9i" movable inla cylindricalcartridge llflf'inr serted into the housingtt" of the injection unit.The cartridge H a" has a normally.- sealed .rubber plug HI 'at-thebottomwhich, upon insertion of the cartridge into the housing 33 15 pierced bya hollow needle l l2to establishcommunication with a tube '93 leading toa headM' from which an injection needles?? projects. The head 94 may beprovided with an adhesive layer 95 at its-lower surface.

A further crow-n 'H3 on:the"wat'ch casing permits winding of the mainspring and setting of thehands inconventional-manner.

The use and operation of the device shown in Figures '7, 8,-and-9 isasfollows:

Preparatory te the" insertion of a. filled cartridge llll into theinje'ction unit, the-power piston 101 'is moved into itsextremeposition-by withdrawing --the shaft 04 into the position 8grasping. the --CTOWI1i l 08,: turning lthe shaft approximately 180until the teeth 01513116 rack 103 disengage from the pinion [02, movingthe shaft I04 longitudinally and re-engaging the teeth of the rack lfl3with the pinion H12. Anlled cartridge is theninserted into the housing63'. and the housing is screwed onto the, powerv unit at 81" whereby thebottom plug vI'll of the cartridge :is automatically pierced.

The running watch mechanism. causes the shaft [OI-and its pinion I02 *toturn slowly urging the power piston I01 against thev piston .91"wherebythe medicinal fluid'in the cartridge is gradually dischargedthrough the 1 injection needle at a constant rate; When the piston 91"reaches-the bottom of the cartridge I Hi, the cartridge is empty and thewatch comes to a stop. The-total timeof the treatment maybe read at thedialwhich also furnishes a continuous indication .of the progress of-thetreatment while the device is in operation. Inthehereinbeforedescribed.forms of syringes the power ioroperating themechanism is derived from Springs initially placed under tension. Thereare, of course; other iorms of-power available which lend themselves touse in syringes according to the invention;

Motive power may, for eXampIe -be -derived from gas or'vaporpressure. Aself contained disposable unit utilizinggas or vapor-pressure asoperating power is illustrated in Figure 10. It consists of asubstantially cylindrical shell H4 of'sheet metalshaped to provideinwardly extending flanges I I5 and M6 for holding :the'elements of thedevice in pressuretight assembled position.

Adish-shapedupper-disk I IT is filled with a charge of a highly viscousliquid 1 l8 covered-and sealed by a metal diaphragm H9. A chamber [20 isformed above-the diaphragm 1 l9 -by.a pressure resistantdome-shapedsheet metal wall l2]. The-chamber |2G contains a charge-of propane,methyl chloride or other liquid which at body temperatures partlydevelops sufiicient operating Pressure." 7

A restricted-passage 1.22 leads through the upper disk 1 l1 and isiormedby a screw .l23 threaded into an aperture 124- with'sufiicientclearance to providea helical-passage of'capillary flow characteristicsabout the screw [23. 'The lower disk: 125 also substantially of dishshape lies arranged below the upper disk H1 and is sealed with respectto the capillary passage I22 by a flexiblediaphragm 12E of rubber orother resilient material. The diaphragm |25 separates the viscous liquidentering through the restricted passage l 2-2 from the charge.of-medicinal fluid contained'in the cavity ofzthe lowerdisk at I21. Themedicinal fluid may bedischarged through an injectionneedle I2 8.

The device of Figure --10 is assembled under pressure and is'closed by apressuretight cap 2| fitting on a knob-shaped seat 2| through whichthe-needle 128 projects. Th viscous liquid which transmitspressurefrom-the-upper side of the upper disk to its lower side, iwholly contained in the space above the disk" H 1 and the medicinalliquid is in the'chamber I21.

Shortly'before applicatiomof the device to the body of a patient, thecap- 2 l is removedcausing medicinal fluid to be discharged through theneedle I23. Viscous liquid is now being forced through'the restrictedpassage 422 and-causes furtherfiuid to bedischargedthrough-theneedleshown in' Figure 73 'Ihis is-accomplished by 75 128... The'action-ofthedevice continue uni-l1 n of the viscous liquid haspassed through'therestricted passage l22,, whereafter the-diaphragm tient; by bandagesOrtape-and may again be providedon its ,underside with -an adhesivesubstance to keep itfirmly in place. j "1 Because of the slow rate ofinjection provided by'the devices embodying the present invention, it isnotnecessa-ry to use long or relatively thick injection needles, butneedles as small as, onesixteenth of aninch in lengthand-one-sixtyfourth of an inch in diameterxare satisfactory. Suchneedles need not extend into the muscular tissue, but insertion into theskin is sufficient. This greatly reduces the discomfort'of the patientwho may move about andeven go about his regular business withoutbeingdisturbed by the needle.

Compared to conventional methods of injection, the invention providesvarious advantages. Whereas, according: to conventional injection Ipractices, the location of an injection needle is relatively critical,for example in a muscle or vein, it is sufiicient in practicing theinventionto insert the needle into the skin, the location of thespecific point of injection being not critical because of the slowinjection rate.

I Thus, any

portion of thebody may be selected where the automatic device is mostconvenient to carry],

According to conventional injection practices,

relatively large volumes of fluid are injected per unit of actualinjection time, for example, a volume of one or two cc. over a period offive or ten seconds This ratio is favorably altered by the presentinvention where the quantity of liquid injected within the. same periodof time is infinitesimal and 'canonly be expressed in terms ofmilligrams. The reduced injection rate makes the process of injectionfar less uncomfortable than present practices where the forming of poolsof liquid in the tissue is frequently very painful.

According to the best of my information the drip method of intravenousinjections is'the only continuous injection practice used at. present.In this method relatively large volumes of diluent are employed which,after injection, must be eliminated from the system of the patient. Thepresent invention does not impOse on the patient the burden ofeliminating large volumes of a diluent since none is employed. Medicinalpreparations of relatively high concentration may be used, with safetybecause of the exceedingly slow injection rate.

The invention thus provides a greatly improved injection device whichopens upan advanced form of treatment techniques havingnu merousadvantages; 'The introduction intoa patients system of medicinalcompositionscontinuously and at a substantially constant slow raterequires considerably less medication than if individual doses areinjected periodically and the total toxic effect is correspondinglyreduced. 7

The inventionis particularly suitedfor the injection of liquids,semi-liquid fluids, and suspensions, for example penicillin suspensionsincluding beeswax and peanut-oil. Penicillin is diflicult to administerbecause of its limited stability in liquid form. In suspension'it isadmirably suited for administration according tothe present invention.

The invention provides great economy in that the services of a physicianor trained nurse are required only once when the injection device is :7

professional services: Q According to conventional practice, theelements of asyri'ng'e have to be sterilized,repeatedly, 1 once for eachinjection.

According to the invention, 'asterile, ready-touse injection syringetakes the place of the great number of single-shot syringes.

. The present invention permits medication at a substantially constantrate as well as at gradually increased or decreased rates by properselection of the source of operating power, for example by selection ofa spring or spring assembly or other source of power of predeterminedcharacteristics.

The temperature coefiicient of the viscous liquid employed bythe varioustypes of syringes or the temperature coeflicient of the hair spring intheescapement of the power unit of the device shown in Figures '7 to 9,or the temperature coefficient of other time controlling means may be soselected as to provide a compensating action, for example, to cause anincrease or a decrease in the rate of injection in accordance with thechange in the patients body temperature.

moval oftherelease stem50., The piston 41 advances immediately under theaction of the spring 53 due to compressibility. of the air bubble in thechamber, and an initial relatively large volume of medicinal fluid is 7injected. After compression of'the air bubble, the rate of injectionisreduced and remains substantially constant during the'remainder ofthe operation of 'Fh i -Lfi In the various forms of' automatic syringesillustrated in the drawings, the operating power available for expellingthe rnedicinal fluid is vastly -greater than [the actual power requiredforimoving the movable wall which reduces the volume of the chambercontaining the medicinal fluid. The pressure in the chamber containingthe viscous fluid isfor' this reason much greater than the pressure inthe chamber containing the medicinal fluid. I For example, the pressurein the chamber' c'ontainingtheviscous fluid may be of the order ofeighty pounds per square inch, whereas the pressure in achambercontaining the medicinal'fluid may be of the order of onehalfpound per square inch. This relationship of pressure provides anamplesafety margin, so that variations in the friction of the piston inthech'amb'er containing the medicinal-"fluid will not affect thefunctioning of the device. 'Assumporarily needed; it is easilyseen' thatsuch increases in'required'power-are still farbelow the availablezmotivepower, that is eighty pounds in the specificexample.

This relationship also exists in the clockework operated form of syringeWhere the power; moving the piston is vastly in excess of. the power irequired; for expelling the medicinal fluid: 1 1. r

. 1,Obviouslygthe.presentinventionis not limited to; the particular;embodiments herein shown and described. "Various changes;=mod-iflcations, substitutions, additions, omissions *will'suggestthemselves to persons skilled in the art as a result of the teaching of*the invention. Such changes therefore do not involve'a departure fromthe spirit and the teachingsof this invention.

What is claimed is:

1 An automatic syringe for the injection of fluids into body tissuescomprising, in combination, a housing adapted to becarried by thepatient; a movable wall in said housing forming a variable volumechamber therein for containing a charge of fluidto be injected; meansfor forming a discharge passage from'said chamber includinganinjectionneedle; a source of motive power insaid housing tor moving saidmovable wall in adirection to reduce the volume of said chamber anddischarge fluid therefrom; means for retardingtherate of movement ofsaid wall said retarding means including two further chamberscommunicating with each other through a restricted passag at least ,oneof said two further chambers having a movable wall acted upon bysaidsource in-a direction to reduce the volume of saidone chamber, and acharge of viscous .liquidflin said last named one chamber. a

2. An automatic syringe-for the injection of fluids into bodytissue-comprising, in combination, a housing'adapted to be attached to aportion of the patientsbody; a movable wall in said housing forming avariable volume chamber therein for containinga charge of fluid to beinjected; an injectionv needle mounted on said housing and communicatingwith said chamber through apassagepa-"source of motive power in saidhousing for acting ,on said movable wall to reduce the volume of saidchamber and discharge fluid therefrom; means for controlling the rateoimovement of said wall including a further chamber having. a movablewall acted 7 upon by said source in a direction to reduce the volume ofsaid further chamber'and having a restricted passageleading therefrom,and a charge of viscous liquid in said further chamber; and means forreleasing said source of motive power at will, the charge-of viscousliquid, and the restricted passage being on the same side of saidmovable wall in the direction of movement thereof by-the-motive powersource.

3. An automatic syringe for t1 rv injectionoi fluids into-bodytissuecomprising in combination, a housing adapted to be attached to a portionof the patients body; a piston novable in said housing; formingthemovable wall of a variable volume chamber therein for containing acharge of fluid to be injected; means forming a d s har e passa e om aidchamber i ing an injection needle; a spring in said housing adaptedtoact on said piston. formoving said piston in adirection to reduce'thevolume of said chamber and dischar e fluid therefrom; and means forcontrolling the'rate of movement of said piston, said rate controllingmeans includ ingga. further-chamber having a movable wall acted upon 'bysaid spring in. a direction to reduce the Volumeztiof said furtherchamber by said spring, said further chamber having a restricted passageleading therefrom, and a charge of viscous liquid in said furtherchamber, the charge of viscous liquid, and the restricted passage, beingon the same side of said piston in the direction of movement thereof bysaid spring.

4. An automatic syringe for the injection of tion, a housing adapted tobe carried by the patient; a movable wall in said housing forming avariable volume chamber therein for contain ing a charge of fluid-to-beinjected; means forming a discharge passage from said chamber includingan injection needle; a source of motive power in said housing for actingon said movable wall in a direction to reduce the volume of said chamberand discharge'fluid therefrom and means responsive to lapse of time forretarding the movement of said movable wall under influence of saidsource to'a predetermined controlled substantially constant rate.

5. An automatic syringe for the injection of fluids into body-tissue,comprising, in combination, a first and a 'second housing attachabletogether to form'aunit, theunit being adapted to be attached to a,portion of the patients body; a movablewall in said first housingforming a variable volume chamber thereinior containing a charge offluid tobeinjected; means forming a dischargepassage "from said chamberincluding an injection needle; a-source of motive power in said secondhousing adapted to act on said movable wall in said'first housing toreducethe volume of said chamber and discharge fluid therefrom; andmeans'in'said second housing responsive to lapse oftime forautomatically retarding said ,source'of power to a'predeterminedcontrolled substantially; constant rate, whereby a substantially uniformrate of fluid discharge from said chamber may be obtained over anextended vperiod of time.

6. In a syringe'for the injection of fluids into body tissue, thesyringe containing a housing, a variable volume chamber in said housingfor containing'fluid to be injected, an injection needle communicatingwithflsaid chamber, and power means including a source of motive'powerin said housing for reducing the volume of said chamher to dischargefluid from said chamber through said needle, the improvement whichcomprises a housing having a substantially flat surface adapted to beplaced against a portion of the patients body and, to be attachedthereto; and means in saidhousing responsive to lapse of time forautomatically retarding the action of said housing for automaticallyretarding the action of said power means to a. predetermined controlledsubstantiallyconstant rate to obtain a predetermined slow rate of fluiddischarge over an extended period of time.

'7. In a syringe for the injection of fluid into body tissue, thesyringe containing a housing, a variable volume chamber in said housingfor containing fluid tobe injected, an injection needle communicating,with said chamber, and power means including a source, of power in saidhousing for discharging vfluid from said chamber through said needle,the improvement which comprises a housing having a flat surface adaptedto be placed flat against a portion of the patients body and to beattached thereto, said needle being mounted on said housing andprojecting above said surface in a direction substantially normal withrespect to said surface; and, in said housinggmea'ns responsive to lapseof time for automatically retarding the action of said power means to apredetermined controlled substantially constant .rate to obtain apredetermined slow rate of fluid discharge over an extended period oftime.

PAUL KOLLSMAN.

(References-on following page) 14 Name Date Douglas Jan. 26, 1943 LoweMar. 1, 1949 FOREIGN PATENTS Country Date I Great Britain Dec. 20, 1944OTHER REFERENCES Owen: Needle Holder for Thoracooentesis, BritishMedical Journal (clipping), September

